1. Field of the Invention (Technical Field)
Embodiments of the present invention relate a circuit that boosts battery voltage for low current draw devices, particularly for flashlights.
2. Description of Related Art
Over a billion people in third world countries do not have access to household electricity, resulting in a reliance on devices powered by expensive batteries. Given the average third world wage of a few dollars a day, 20-30% is spent on energy sources like batteries, creating a desperate need for improving battery lifetime. Batteries that, at a glance, are considered to be “dead” are discarded even though they still have remaining energy
Embodiments of the present invention solve this problem by incorporating a “Joule Thief” circuit (which boosts battery voltage) into low current draw devices, such flashlights, cell phones, laptops, tablets, radios, battery operated toys, mp3 players, two way radios, wireless electronics like keyboards and mice, game controllers, cars, remote controllers for TV's, stereos, etc., to utilize remaining energy in batteries that are otherwise considered “dead” when used in these devices, thus extending battery life. For instance, conventional light-emitting-diodes (LED) flashlights, such as those commercially sold in department stores and on the Internet, most often require anywhere from one to six AAA, AA, C, or D size batteries for proper function, and comprise of one or more LEDs lights that provide illumination when the flashlight is turned on. A common flashlight provides useful illumination from the battery source until the batteries become discharged to a point that the amount of illumination is no longer useful and the batteries are either replaced or recharged. There is a need for devices that can utilize the energy that remains in the batteries.
Embodiments of the invention use a simple and inexpensive circuit, which can be incorporated into low current draw devices, allowing the remaining energy in a “dead” battery to be used. This type of circuit takes a low voltage source (“dead” batteries), steps it up to a higher voltage using a toroid as an inductor (similar in function to a step up transformer) and then rapidly discharges a voltage pulse to the component of the device needing power, doing this several hundred to several hundred thousand times a second by using the transistor as a fast switch. While the circuit is turning on and off very rapidly, it appears as if the device is continually on. By stepping up the voltage from a “dead” battery, the user can drain the last amount of energy from it and use it to power the device. This is energy which would otherwise be wasted. Embodiments of the invention for optimized Joule Thief circuit designs cost pennies to retrofit in current devices when produced in bulk, paying for themselves in the first set of batteries. In one embodiment, a voltage sensing circuit is added that automatically senses when the battery source voltage drops below a useful value, and automatically engages a voltage increasing electronic circuit. Embodiments of the invention do not only significantly reduce energy costs for people in third world countries, they reduce battery landfill pollution through the extension of battery life.